Xiegu X6100 Repair

A Crystal Palace club member brought along an X6100 transceiver with a receiver which was not able to clearly receive members of the club 6m net less than 10 miles away. Putting the unit on the test bench revealed that a minimum input signal of 1 millivolt (mV) was required to open the squelch. I was not hopeful of a successful repair of this unit as no circuit diagram was available but thought it worthwhile to investigate the problem.

The covers were removed and the main batteries disconnected. Care is needed here as there are two different lengths of fixing screws. The mounting screws holding the PC boards (PCBs) together were carefully removed and the PCBs folded out flat on the bench top. The batteries were reconnected and the unit switched on - be careful with the small PCB that connects the batteries together - if in doubt wrap it in an insulating material. The signal generator was connected to a coaxial lead with one end having open but insulated wires. Offering the centre lead up close to the band switching relays it became obvious that the signal suddenly disappeared when moving the wire closer to the input BNC socket.

Inspecting the solder joints under the band change relays a few of the joints looked suspicious with an irregular finish so the battery was disconnected and using a very small 700 degree Faranheit bit (4PTF7-1) in my Weller TCP-1 soldering iron I briefly touched the tip of the bit onto each solder joint. Several of the joints gave off some smoke suggesting that there was some flux remaining in the joint.

Reconnecting the battery and connecting the signal generator to the BNC socket showed that the receiver sensitivity had improved to the point where an 0.6microvolt (uV) signal now opened the squelch.

The battery was disconnected and the PCBs reassembled. The battery was reconnected and the metal covers replaced with the correct length screws - be careful to ensure that the loose wires are not trapped under the covers. Retesting showed that the receiver was now working correctly and resolving a 1 uV narrow band FM signal. The other bands showed similar sensitivities.

The club member is now able to clearly hear all of the net participants and HF band amateur signals are now audible with the short aerial provided with the unit.